RFID device and method of making

ABSTRACT

A radio frequency identification (RFID) device includes a conductive pattern, such as an antenna, on one side of a substrate, and a chip, such as part of a strap, electrically coupled to the conductive pattern, and either on an opposite side of the substrate or on the same side of the substrate as the antenna. A method of fabricating the RFID device may include crimping the strap onto the substrate, in contact with a seed layer, which is subsequently used in forming the antenna or other conductive pattern by plating. The seed layer may be a patterned conductive ink layer. Alternatively, the seed layer may be a layer of conductive material deposited on the substrate, such as by vacuum deposition. Parts of the deposited layer may be covered with a patterned mask in order to form the desired configuration of the conductive pattern.

This application is a division of U.S. application Ser. No. 10/634,243,filed Aug. 5, 2003, now U.S. Pat. No. 7,120,987 which is herebyincorporated by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

The invention relates radio frequency identification (RFID) devices andmethods of making such devices.

DESCRIPTION OF THE RELATED ART

Radio frequency identification (RFID) tags and labels (collectivelyreferred to herein as “devices”) are widely used to associate an objectwith an identification code or other information. RFID devices generallyhave a combination of antennas (a conductive pattern) and analog and/ordigital electronics, which may include for example communicationselectronics, data memory, and control logic. For example, RFID tags areused in conjunction with security locks in cars, for access control tobuildings, and for tracking inventory and parcels. Some examples of RFIDtags and labels appear in U.S. Pat. Nos. 6,107,920, 6,206,292, and6,262,692, all of which are hereby incorporated by reference in theirentireties.

As noted above, RFID devices are generally categorized as labels ortags. RFID labels are RFID devices that are adhesively or otherwise havea surface attached directly to objects. RFID tags, in contrast, aresecured to objects by other means, for example by use of a plasticfastener, string or other fastening means.

One goal in the fabrication of RFID devices is improving methods bywhich such devices are fabricated.

SUMMARY OF THE INVENTION

According to an aspect of the invention, an RFID device has an antennaand a strap. The antenna and the strap are electrically coupled togethervia crimped connections.

According to another aspect of the invention, a method of making an RFIDdevice includes forming a seed material on a substrate, and attaching astrap to the substrate, wherein the strap is electrically coupled to theseed layer via conductive connections through the substrate.

According to yet another aspect of the invention, a method of making anRFID device includes depositing a metal layer on a substrate, coveringportions of the metal layer with a patterned mask of dielectricmaterial, and plating to form an antenna on the uncovered portions ofthe metal layer.

According to still another aspect of the invention, a method of making aradio frequency identification (RFID) device, includes: forming aconductive seed layer on a substrate; and attaching a strap to thesubstrate, wherein the attaching includes crimping to form crimpedelectrical connections between the seed layer and conductive leads ofthe strap.

According to a further aspect of the invention, a radio frequencyidentification (RFID) device includes a substrate; a patternedconductive layer on the substrate; a strap; and at least one crimpedelectrical connection between the strap and the patterned conductivelayer.

To the accomplishment of the foregoing and related ends, the inventioncomprises the features hereinafter fully described and particularlypointed out in the claims. The following description and the annexeddrawings set forth in detail certain illustrative embodiments of theinvention. These embodiments are indicative, however, of but a few ofthe various ways in which the principles of the invention may beemployed. Other objects, advantages and novel features of the inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF DRAWINGS

In the annexed drawings, which are not necessarily to scale:

FIG. 1 is a plan view of an RFID device in accordance with the presentinvention;

FIG. 2 is a bottom view of the RFID device of FIG. 1;

FIG. 3 is a side cross-sectional view of part of the RFID device of FIG.1;

FIG. 3A is a side cross-sectional view of part of a first embodiment ofthe RFID device of FIG. 1;

FIG. 3B is a side cross-sectional view of part of a second embodiment ofthe RFID device of FIG. 1;

FIG. 3C is a side cross-sectional view of part of a third embodiment ofthe RFID device of FIG. 1;

FIG. 3D is a side cross-sectional view of part of a fourth embodiment ofthe RFID device of FIG. 1;

FIG. 3E is a side cross-sectional view of part of a fifth embodiment ofthe RFID device of FIG. 1;

FIG. 3F is a side cross-sectional view of part of a sixth embodiment ofthe RFID device of FIG. 1;

FIG. 3G is a side cross-sectional view of part of a seventh embodimentof the RFID device of FIG. 1;

FIG. 4 is a high-level flowchart of a method in accordance with thepresent invention for producing the RFID device of FIG. 1;

FIG. 5 is a flowchart of one embodiment of the method of FIG. 4;

FIG. 6 is a plan view of a first step in the method of FIG. 5;

FIG. 7 is a side cross-sectional view of the first step;

FIG. 8 is a plan view of a second step in the method of FIG. 5;

FIG. 9 is a side cross-sectional view of the second step;

FIG. 10 is a bottom view of a third step of the method of FIG. 5;

FIG. 11 is a side cross-sectional view of the third step;

FIG. 12 is a plan view of a fourth step of the method of FIG. 5;

FIG. 13 is a side cross-sectional view of the fourth step;

FIG. 14 is a plan view of a fifth step of the method of FIG. 5;

FIG. 15 is a side cross-sectional view of the fifth step;

FIG. 16 is a schematic view of a system for carrying out the method ofFIG. 5;

FIG. 17 is a flowchart of a second embodiment of the method of FIG. 4;

FIG. 18 is a plan view of a first step of the method of FIG. 17;

FIG. 19 is a side cross-sectional view of the first step;

FIG. 20 is a bottom view of a second step of the method of FIG. 17; and

FIG. 21 is a side cross-sectional view of the second step.

DETAILED DESCRIPTION

A radio frequency identification (RFID) device includes a conductivepattern, such as an antenna, on one side of a substrate, and a chip,such as part of a strap, electrically coupled to the conductive pattern,and either on an opposite side of the substrate or on the same side ofthe substrate as the antenna. A method of fabricating the RFID devicemay include crimping the strap onto the substrate, in contact with aseed layer, which is subsequently used in forming the antenna or otherconductive pattern by plating. The seed layer may be a patternedconductive ink layer. Alternatively, the seed layer may be a layer ofconductive material deposited on the substrate, such as by vacuumdeposition. Parts of the deposited layer may be covered with a patternedmask in order to form the desired configuration of the conductivepattern. Subsequent to the plating, the mask may be removed, and etchingmay be performed to remove parts of the deposited layer that are notplated because they were covered by the mask.

Referring initially to FIG. 1, a radio frequency identification (RFID)device 10 having a substrate 12 is shown. As shown in FIGS. 1 and 3, ona first or front surface or face 14 of the substrate 12, the RFID device10 has a conductive pattern such as an antenna 16.

A strap 20 is on a back or second surface or face 22 of the substrate12. The strap 20 includes a chip 26 and conductive leads 28 and 30. Theconductive leads 28 and 30 are electrically connected to the antenna 16,through the substrate 12, via conductive crimped connections 32 and 34,respectively. The crimped connections 32 and 34 are connected to a seedmaterial or layer 36, upon which the antenna 16 is formed, such as byplating. As described further below, the seed material 36 may be aconductive ink, or may be a deposited material, such as copper placed onthe front surface 14 of the substrate 12 by vapor deposition.

FIG. 3 shows a generalized representation of the crimped connections 32and 34. Various embodiments of the crimped connections 32 and 34 arediscussed in greater detail below.

Although FIGS. 1-3 illustrate an embodiment with the strap 20 on thesecond face 22 of the substrate 12, it will be appreciated that thealternatively strap 20 may be on the first face 14, the same side of thesubstrate 12 as the antenna 16.

Examples of suitable materials for the substrate 12 include paper andsuitable polymers such as polycarbonate, polyvinyl chloride,polystyrene, polymethyl methacrylate, polyurethane polyimide, polyester,cyclic polyolefin polymers, polyether sulfone (PES), polyethyleneterephthalate (PET), polyethylene naphthalate, polycarbonate,polybutylene terephthalate, polyphenylene sulfide (PPS), polypropylene,polysulfone, aramid, polyamide-imide (PAI), polyimide, aromaticpolyimides, polyetherimide, acrylonitrile butadiene styrene, andpolyvinyl chloride. Further details regarding suitable substrates andsubstrate materials may be found in International Publication Nos. WO00/46854, WO 00/49421, WO 00/49658, WO 00/55915, and WO 00/55916, theentire disclosures of which are herein incorporated by reference.

The leads 28 and 30 of the strap 20 operatively coupled to chip contactsof the chip 26. The chip 26 may include any of a variety of suitableelectronic components, such as the circuitry described above formodulating the impedance of the RFID device 10. The leads 28 and 30 maybe completely made out of an electrically conducting material, such asbeing made out of a metal foil. Alternatively, the leads 28 and 30 mayinclude an electrically insulating material, for example being plasticcoated with metal. The strap 20 may include a strap substrate that isattached to the leads 28 and 30. The strap substrate may be made of anyof a variety of suitable materials, for example, suitable flexiblepolymeric materials such as PET, polypropylene or other polyolefins,polycarbonate, or polysulfone.

The strap 20 may be any of a variety of commercially-available straps.The term “strap,” as used herein, refers broadly to devices that includea microchip or other electronic circuitry, coupled to conductive leads.The conductive leads may be connected to contacts on the microchip orother circuitry by any of a variety of suitable methods. The conductiveleads may include of any of a variety of suitable conductive materials,such as metal strips or deposited conductive ink layers. Examplesinclude an RFID strap available from Alien Technologies, and the strapmarketed under the name I-CONNECT, available from Philips Electronics.Alternatively, the strap 20 may be other than a commercially-availablestrap.

The crimped connections 32 and 34 may include conductive material fromthe seed material 36 or from the conductive leads 28 and 30. Inaddition, the crimped connections 32 and 34 may include conductivematerial added during the plating process used to form the antenna 16.For example, the plating may partially or completely fill, withconductive material, holes made during the crimping process. Suchadditional plated conductive material may make or strengthen theconductive connection between the antenna 16 and the conductive leads 28and 30.

FIGS. 3A-3G show details of various embodiments of the crimpedconnections 32 and 34 between the conductive leads 28 and 30, and theseed material 36. In FIG. 3A the crimped connections 32 and 34 areformed by driving conductive material 38 (parts of the conductive leads28 and 30), which may be made of metal, through the substrate 12. Theconductive material 38 may be driven through the substrate 12 by apierce or punch that passes through the conductive leads 28 and 30, andthe substrate 12. The conductive material 38 may be bent to form crowns40 and 42 in contact with the seed layer 36. Subsequent plating may addmaterial and strengthen the connections between the conductive material38 and the seed layer 36, and/or between the conductive material 38 andthe remaining parts of the conductive leads 28 and 30. Plated materialmay form in the hole left by the punch or pierce, and may fill physicalgaps between conductive materials, and/or provide a physically andelectrically stronger path between the conductive leads 28 and 30, andthe seed layer 36.

FIG. 3B shows the crimped connections 32 and 34 on the first or frontside 14 of the substrate 12. A pierce or punch is used the driveconductive material 38 of the conductive leads 28 and 30 through theseed layer 36 and the substrate 12. The driving of the conductivematerial 38 secures the conductive leads in contact with the seed layer36. In addition, the conductive material 38 may make electricalconnections between the conductive leads 28 and 30, and correspondingparts of the seed layer 36. Subsequent plating may fill gaps between theconductive leads 28 and 30 and the seed material 36 with additionalconductive plated material, thereby improving the electrical connection,for example by reducing resistance or improving reliability of thecontact. In addition, plating may provide an additional connectionbetween the seed layer 36 and edges of the conductive leads 28 and 30.

The straps 20 used in the connections shown in FIGS. 3A and 3B may havemetal conductive leads 28 and 30. An example of such a strap is theI-CONNECT strap referred to above.

FIGS. 3C and 3D show alternative configurations, each differing fromthose shown in FIGS. 3A and 3B in that a potion of the strap 20 residesin a hole 43 in the substrate 12. The hole 43 may be made, for example,by punching, to remove a part of the substrate 12 at a suitablelocation. It will be appreciated that by locating a portion of the strap20 in the hole 43, the strap 20 may have a lower profile on thesubstrate 12. The may make for a less obtrusive device, and/or mayfacilitate subsequent fabrication operations.

In FIG. 3E the strap 20 had a strap substrate 44 upon which theconductive leads 28 and 30 are located. The strap substrate may be asuitable polymer material, such as those discussed above with regard tothe substrate 12. The conductive leads may be formed from a suitableconductive ink material. An example of such a strap is the Alien strapreferred to above.

In making the crimped connections 32 and 34, thin metal rods 46 and 48pierce the conductive leads 26 and 28, the strap substrate 44, thesubstrate 12, and the seed layer 36. The ends of the rods 46 and 48 arethen bent to secure the strap 20 to the substrate 12, and to makecontact with the conductive leads 26 and 28, and the seed layer 36.Subsequent plating strengthens the connections between the rods 46 and48, and the conductive leads 26 and 28 on one side, and the seed layer36 on the other side.

The metal rods 46 and 48 may include a suitable conductive metal, suchas copper and/or nickel. The metal rods 46 and 48 may have a rectangularcross-section shape, for example 2 mm×0.5 mm. However, it will beappreciated that the metal rods 46 and 48 may have a variety ofcross-sectional shapes and dimensions.

FIGS. 3F and 3G shows two other configuration for the crimpedconnections 32 and 34. The substrate 12 and the seed layer 36 have slitsor holes 49 cut therethrough. The conductive leads 28 and 30 arethemselves inserted through the slits or holes 49, with ends of theleads 28 and 30 being bent (crimped) to secure the strap 22 to the restof the device 10. Contact between the leads 28 and 30, and the seedlayer 36 forms electrical connections. The electrical connection may bemechanically and/or electrically reinforced by subsequent plating. Thestrap 20 may be attached on the same side of the substrate 12 as theseed layer 36 (FIG. 3F), or on an opposite side of the substrate 12 asthe seed layer 36 (FIG. 3G).

FIG. 4 shows a high-level flow chart of broad outlines of a method 50for fabricating the RFID device 10. In step 52, the seed material 36 isformed on the front surface 14 of the substrate 12. As will be describedbelow in greater detail, the seed material 36 may be a patternedconductive ink, or may be a substantially-uniform layer of conductivematerial, such as vapor deposited copper, with a patterned maskthereupon.

In step 54, the strap 20 is connected to either to the front 14 or tothe back 22 of the substrate 12 and is electrically coupled to the seedmaterial 36 by a crimping operation. Finally, in step 56, the antenna 16or other conductive pattern is formed upon the seed layer 36, using asuitable plating process, such as a suitable electroplating process.

The general outline of the method 50 having just been given, details arenow given of a pair of specific embodiments of the method 50. FIG. 5shows a high-level flowchart of a method 50 a that involves avacuum-deposited metal layer. FIGS. 6-15 illustrate some of theoperations of the method 50 a.

In step 62 of the method 50 a, a layer 64 of conductive material isdeposited on the front surface or face 14 of the substrate 12. In aparticular embodiment, the deposited layer 64 may be vacuum-depositedcopper having a thickness of about 2000 Angstroms, or more broadly fromabout 100 Angstroms to about 10,000 Angstroms. As an alternative tocopper, the deposited material may include any of a variety of suitableconductive metals, for example aluminum and/or nickel. It will beappreciated that other suitable conductive materials may be employed inthe deposited layer 64.

The deposition of the deposited layer 64 may utilize any of a variety ofmethods, including vapor or vacuum deposition, sputtering, physicalvapor deposition, chemical vapor deposition, or other suitableprocesses.

In step 68, illustrated in FIGS. 8 and 9, a patterned mask 70 is printedor otherwise formed on the deposited layer 64, masking portions of thedeposited layer 64 upon which plating is not desired. The portions ofthe deposited layer 64 left exposed after formation of the mask 70correspond to the pattern of the antenna 16 to be formed in a subsequentstep. The pattern of the mask 70 thus may be a reverse image of theantenna or other conductive pattern 16 to be formed.

The printing in step 68 may be any of a variety of suitable printingprocesses, including inkjet printing, flexo printing, gravure printing,or screen printing.

The ink or other material of the mask 70 is any suitable non-conductivematerial. The material for the mask 70 may be any of a variety ofsuitable materials such as suitable oils, or resist materials such asphotoresist. The mask 70 may include a material that isalkaline-strippable or is soluble in another suitable solvent forremoving the mask 70. Examples of suitable alkaline-soluble resistsinclude Enthone PR3011, available from Ethone, Inc., and CGSN 7005,available from Coated Circuit Products of England. Examples of suitablesoluble resists include Enthone PR4011, available from Ethone, Inc., andCGSN 7011, available from Coated Circuit Products.

It will be appreciated that, in order to make for a more efficientprocess, the mask 70 may be merely printed in a patterned print upon theconductive deposited layer 64. Alternatively, the mask 70 may be formedin a variety of other suitable ways, such as coating with a resistmaterial, followed by selectively removing portions of the resistmaterial to expose parts of the underlying conductive deposited layer64. The methods of selectively removing portions of a material mayinclude suitable lithographic methods.

Thereafter, in step 74, the strap 20 is crimped substrate 12, asillustrated in FIGS. 10 and 11. As illustrated, the strap 20 is crimpedonto the back surface 22 of the substrate 12, but it will be appreciatedthat alternatively the strap may be crimped to the front surface 14 ofthe substrate 12. The crimping provides electrical crimped connections32 and 34 between conductive leads 28 and 30 of the strap 20, and thedeposited layer 64. As seen in FIG. 11, the crimped connectionscorrespond to exposed portions 76 and 78 of the deposited layer 64, thatis, portions not covered by the mask 70.

The crimping may be performed to make the crimped connections 32 and 34shown in FIG. 3A and discussed above, by using a pierce to driveconductive material from the conductive leads through the substrate 12and the seed layer 36, and by using a cone-shaped device to form thecrowns 40 and 42 (FIG. 3A).

The crimping to make the crimped connections 32 and 34 shown in FIG. 3Emay be made by using a device similar to a stapler to drive the metalrods 46 and 48 (FIG. 3E) through the device 10, and bend the ends of themetal rods 46 and 48 to bring them into contact with the seed material36 and the conductive leads 26 and 28. In fact, standard staples and astandard stapler may be used to make crimped connections similar tothose shown in FIG. 3E.

Other of the various connections shown in FIGS. 3A-3G may be made bysuitable methods.

As shown in FIG. 11, the strap 20 may be located relative to thesubstrate 12 such that the chip 26 of the strap 20 is facing away fromthe substrate. It will be appreciated that other configurations arepossible, for example, with the strap 20 facing towards the back surface22 of the substrate 12, or with the chip 26 being embedded within thestrap 20.

In step 80, illustrated in FIGS. 12 and 13, a plating process is used toform the antenna or other patterned conductive layer 16. Thesubstantially-uniform deposited conductive layer 64 provides a way ofdividing even current flow across the exposed areas (such as the regions76 and 78) of the deposited layer 64. Thus, a substantially uniformthickness may be obtained in the antenna or other conductive pattern 16formed by the electroplating process.

Copper may be plated to form the antenna or other conductive pattern 16.Also, the material to be plated may be selected so as to be the same asthe material of the conductive deposited layer 64.

The substantially uniform conductive deposited layer 64 provides a lowelectrical resistance when used in the plating process to form theantenna or other conductive pattern 16.

In step 84, illustrated in FIGS. 14 and 15, the mask 70 is removed. Themask 70 may be removed by any of a variety of suitable processes, forexample, by washing the RFID device 10 using a suitable solvent. Asnoted above, the mask 70 may include an alkaline-strippable material,which may be removed merely by washing with an alkaline solution.

Finally, in step 88, etching is performed to remove portions of thedeposited layer 64 not covered by the antenna or other conductivepattern 16. The etching may be accomplished by any variety of suitableetching processes, for example including exposure to a liquid, such asan acid that removes the copper or other material of the deposited layer64. An example of a suitable etchant is a suitable ferrous chlorideaqueous solution. As an alternative to wet etching, other suitablemethods of etching may be employed, such as dry etching, plasma etching,or reactive ion etching.

The etching may remove some of the material of the antenna or otherconductive pattern 16. However, the duration of the etching and/orconcentration of the etchant may be controlled, so as to limit theamount of material removed from the antenna or other conductive pattern16, while desirably removing the portions of the conductive depositedlayer 64 that are not covered by the antenna or other conductive pattern16.

The resulting structure of the RFID device, following the etching instep 88, may be substantially similar to that of the RFID device 10shown in FIGS. 1-3 and discussed above. It will be appreciated that,although the antenna or other patterned conductive layer 16 is shown inFIGS. 1-3 as being separate from the underlying seed layer 36, in factthe electroplated material of the antenna or other conductive pattern 16may form a unitary conductive pattern with the underlying portions ofthe deposited conductive layer 64.

Following the etching step 88, a suitable wash may be utilized to removetraces of the wet etchant material employed.

It will be appreciated that many other suitable processes may be,undertaken in transforming the RFID device into a tag or label suitablefor use. Other layers may be added, for example, such as adhesivelayers, printable coating layers, or seeding layers. Additional devicesmay be included on the substrate 12, or may be coupled to the RFIDdevice 10.

Further it will be appreciated that there may be some variation in theorder of steps from that illustrated in FIG. 5. For example, asillustrated, the attaching of the strap 20 occurs after the printing ofthe mask 70. However, it will be appreciated that the printing of themask 70 may occur after attachment of the strap 20, if desired. It willbe appreciated that other suitable modifications may be made to themethod 50 a shown in FIG. 5 and discussed above. Such modifications mayinclude, for example, changing the order of steps, adding additionalsteps, combining multiple of the steps into a single process, orsplitting suitable of the steps into multiple sub-operations.

With reference now to FIG. 16, some or all of the processes of themethod 50 a may be performed in one or more roll-to-roll operations.FIG. 16 shows a system 100 for performing the method 50 a in aroll-to-roll process. In the system 100, substrate material 101 startsat a supply roll 102. The conductive layer 64 is then deposited at adeposition station 104, with the mask 70 printed at a printer 106. Thestrap 20 may then be crimped onto a back surface of the substratematerial 101 using a crimper 110. It will be appreciated that individualof the straps 20 may be brought to the substrate material 101 throughany of a variety of suitable methods. For example, a pick-and-placeoperation may be used to place the strap 20 in a desired position on thesubstrate 12. Reference marks may be utilized to aid in proper alignmentof the strap 20 relative to the exposed portions of the conductivedeposited layer 64. Alternatively, the strap 20 may be temporarilyseparated on a separate web of material that is brought into contactwith the web of substrate material 101 at the desired location.

Following the crimping, the antenna or other conductive pattern 16 isformed in a plating process, for example, by passing the substratematerial 101 through a plating bath 114. The mask may then be removed ina solvent washing application process shown at reference number 118.Then a wet etching may be performed by passing the substrate material101 through an etch bath 120. Finally, the substrate material 101 may begathered in a take-up roll 122.

Further processing may then be performed on the web of substratematerial 101. As noted above, additional layers or structures may beadded. Also, the individual RFID devices 10 may be physically separatedfrom one another and from the web substrate material 101, by a suitablecutting process.

Turning now to another embodiment of the method 50, FIG. 17 shows amethod 50 b for forming the RFID device 10. FIGS. 18-21 illustratevarious processes of the method 50 b.

In step 130 of the method 50 b, a patterned seed layer 136 is printed orotherwise formed on the front surface 14 of the substrate 12, asillustrated in FIGS. 18 and 19. The seed layer 136 may be printed by anyof a variety of suitable printing methods, including screen printing,inkjet printing, or gravure printing. The ink may be any of a variety ofsuitable conductive inks, for example, an ink containing copper and/orsilver particles. Other suitable inks may include inks containing othertypes of conductive metal particles, or inks containing other conductivematerials, such as graphite or suitable conductive polymer materials.

Other methods of forming the patterned seed layer includes patternedvapor deposition of a suitable metal, such as copper. Further details onsuch a process may be found in U.S. Published Application No.2002/0018880, which is herein incorporated by reference in its entirety.

The seed layer 136 corresponds to the desired configuration of theantenna or other conductive pattern 16. In addition, the seed layer 136may have additional elements to provide electrical connection betweenvarious parts of the seed layer 136, so as to allow a more uniformelectroplating process in a subsequent step. For example, if the antenna16 is an antenna for a 13.56 MHz RFID device, the antenna may have alength large enough such that electrical connection between elements ofthe antenna 16 is desirable. One method of making such a temporaryelectrical connection is described in U.S. Pat. No. 6,476,775, which isherein incorporated by reference in its entirety. On the other had, ifthe antenna 16 is a dipole antenna, such as the type used for UHF ormicrowave RFID devices, operating for example at 900 MHz or 2.45 GHz,there may be no need for an additional electrical connection betweenelements or parts of the antenna.

In step 140, illustrated in FIGS. 20 and 21, the strap 20 is crimpedonto the front surface 14 or the back surface 22 of the substrate 12.The crimping forms crimped connections 32 and 34 between conductiveleads 28 and 30 of the strap 20, and elements of the conductive ink seedlayer 136. The crimping may be performed in a similar manner to that asdescribed above with regard to the crimping operation in the method 50a.

In step 150, electroplating is performed to produce the antenna or otherconductive pattern 16. By suitable application of current within asuitable, ion-containing bath, material may be plated upon the seedlayer 136, forming the antenna 16 of a suitable thickness.

After the electroplating, suitable steps may be taken to removeundesired plated areas. For example, acid may be used to removeadditional material between desired elements of the antenna 16. It willbe appreciated that no such removal is necessary when there is noadditional conductive material between desired elements of the antenna16.

It will be appreciated that steps of the method 50 b may also beperformed in one or more roll-to-roll operations. A system may be usedto perform the roll-to-roll operations, with suitable printers,crimpers, and electroplating baths, which may be analogous to thosedescribed above with regard to the system 100 (FIG. 16).

The method 50, in its various embodiments, allows for inexpensiveproduction of the RFID device 10, with its antenna 16 and strap 20 onopposite faces of the substrate 12. As described above, the electricalconnection between the strap 20 and the antenna 16 may be a crimpedconnection through the substrate 12. Such a connection provides goodmechanical strength, as well as being an efficient way to form aconnection. It will be appreciated that the plating operation thatoccurs subsequent to the crimping may provide plated conductive materialat connection points between the crimped connection and the parts of theantenna 16 and the strap 20 to be coupled together.

Although the invention has been shown and described with respect to acertain preferred embodiment or embodiments, it is obvious thatequivalent alterations and modifications will occur to others skilled inthe art upon the reading and understanding of this specification and theannexed drawings. In particular regard to the various functionsperformed by the above described elements (components, assemblies,devices, compositions, etc.), the terms (including a reference to a“means”) used to describe such elements are intended to correspond,unless otherwise indicated, to any element which performs the specifiedfunction of the described element (i.e., that is functionallyequivalent), even though not structurally equivalent to the disclosedstructure which performs the function in the herein illustratedexemplary embodiment or embodiments of the invention. In addition, whilea particular feature of the invention may have been described above withrespect to only one or more of several illustrated embodiments, suchfeature may be combined with one or more other features of the otherembodiments, as may be desired and advantageous for any given orparticular application.

1. A radio frequency identification (RFID) device comprising: asubstrate; a patterned conductive layer on the substrate; a strap; andat least one crimped electrical connection between the strap and thepatterned conductive layer; wherein the at least one crimped connectionpasses through the substrate.
 2. The device of claim 1, wherein thepatterned conductive layer and the strap are on opposite respectivesides of the substrate.
 3. The device of claim 1, wherein the patternedconductive layer and the strap are on the same side of the substrate. 4.The device of claim 1, wherein the at least one crimped connectionincludes a rod that passes through the substrate.
 5. The device of claim4, wherein the rod has a pair of bent ends, one of which is in contactwith a seed layer that is part of the conductive pattern, and the otherof which is in contact with a conductive lead of the strap.
 6. Thedevice of claim 5, wherein the crimped connection also includessubsequently plated material.
 7. The device of claim 6, wherein theplated material is continuously coupled to plated material that is atleast part of the patterned layer.
 8. The device of claim 5, wherein theseed layer is a metal layer.
 9. The device of claim 5, wherein the seedlayer is a conductive ink layer.
 10. The device of claim 1, wherein thecrimped connection includes conductive material displaced from aconductive lead of the strap.
 11. The device of claim 10, wherein thecrimped connection also includes subsequently plated material.
 12. Thedevice of claim 11, wherein the plated material is continuously coupledto plated material that is at least part of the patterned layer.
 13. Thedevice of claim 8, wherein the displaced conductive material includescrowns of conductive material.
 14. The device of claim 1, wherein thepatterned conductive layer includes an antenna.
 15. The device of claim1, wherein the strap includes a chip coupled to the conductive leads.16. The device of claim 1, wherein the substrate is made of a flexiblepolymeric material.
 17. The device of claim 1, wherein at least part ofthe strap is within a hole in the substrate.
 18. The device of claim 1,wherein the crimped connection also includes subsequently platedmaterial added after making of the electrical connection between thestrap and the patterned conductive layer.
 19. The device of claim 18,wherein the subsequently plated material fills a hole in the at leastone crimped connection.
 20. The device of claim 18, wherein thesubsequently plated material fills gaps in the at least one crimpedconnection.